With growing demands for cloud storage and cloud-based network computing applications, high and ultrahigh data rate recording becomes important for near-line and high-end disk drive devices. It is essential to design a PMR writer that can achieve optimum high data rate performance in both area density capability (ADC) and ATI also referred to as adjacent track erasure (ATE).
A PMR write head typically has a MP layer having a MP tip with a small surface area at an air bearing surface (ABS), and coils that conduct a current and generate a magnetic flux in the MP layer such that the magnetic flux exits through the MP tip and enters a magnetic medium (disk) adjacent to the ABS. Magnetic flux is used to write a selected number of bits in the magnetic medium and typically returns to the MP through a trailing loop comprised of a trailing shield structure with a front side at the ABS and a PP3 trailing shield portion that extends over the coils and connects to a top surface of the MP layer above a back gap magnetic connection.
For both conventional (CMR) and shingle magnetic recording (SMR), continuous improvement in storage area density or ADC is required for a PMR writer in order to deliver or pack higher bits per inch (BPI) and higher TPI. An all wrap around (AWA) shield structure that surrounds the MP tip in a PMR write head is desirable in that the trailing shield is responsible for improving down track field gradient while side shields and a leading shield improve the cross track field gradient and TPI as well as ATI performance.
Current PMR writers tend to have the trailing shield (TS) layer in one piece with the same material from center to edge of the trailing shield structure. As depicted in FIG. 1, PMR head performance sits on a line 2 where better TS efficiency (ADC) is typically traded off for better ATI by selecting magnetic materials with different Bs also known as magnetization saturation (Ms). With a high Ms material, the magnetic path driving main pole and trailing shield gains efficiency from low reluctance. However, high Ms materials also lead to more field leakage and worse ATI. Thus, an improved trailing shield design is needed to escape the tradeoff line and approach a point A where both high trailing shield efficiency in terms of improved ADC, and better ATI are realized.